Fungus Fuels Tree GrowthPoplar is the fastest growing hardwood tree in the western United States, making it an energy feedstock of particular interest to the U.S. Department of Energy (DOE). The fungus is almost always found among and within poplar trees, and in an effort to understand its influence on the plant, a team of scientists studied what happens to the tree’s physical traits and gene expression when the fungus is present.

Better Genome Editing for BioenergyCRISPR-Cas9 is a powerful, high-throughput gene-editing tool that can help scientists engineer organisms for bioenergy applications. Cas9 needs guide RNA to lead it to the correct sequence to snip—but not all guides are effective. Researchers created a set of guide RNAs that were effective against 94 percent of the genes in a lipid-prolific yeast.

Cultivating Symbiotic Antarctic MicrobesIn the Proceedings of the National Academy of Sciences, researchers employed multiple microbiology and ‘omics techniques to experimentally determine that Nanohaloarchaeota are not free-living archaea but rather symbionts.

Methane Flux in the AmazonWetlands are the single largest global source of atmospheric methane. This project aims to integrate microbial and tree genetic characteristics to measure and understand methane emissions at the heart of the Amazon rainforest.

Insights into Functional Diversity in NeurosporaThis proposal investigates the genetic bases of fungal thermophily, biomass-degradation, and fungal-bacterial interactions in Sordariales, an order of biomass-degrading fungi frequently encountered in compost and encompassing one of the few groups of thermophilic fungi.

Improving the Cacao Genome and PhytozomeAn updated reference genome for Theobroma cacao Matina 1-6 has now been completed and released by HudsonAlpha scientists, with the help of Mars Wrigley funding. The annotated genome has been updated to a high quality modern standard and includes RNA-seq data. The improved genome is available for comparative purposes on the latest version of the JGI plant portal Phytozome (phytozome-next.JGI.doe.gov).

Mining IMG/M for CRISPR-Associated ProteinsResearchers report the discovery of miniature CRISPR-associated proteins that can target single-stranded DNA. The discovery was made possible by mining the datasets in the Integrated Microbial Genomes and Microbiomes (IMG/M) suite of tools managed by the JGI. The sequences were then biochemically characterized by a team led by Jennifer Doudna’s group at UC Berkeley.

What Happens Underground Influences Global Nutrient CyclesThrough the Facilities Integrating Collaborations for User Science (FICUS) program, the Environmental Molecular Sciences Laboratory (EMSL) and the DOE Joint Genome Institute (JGI) have selected 11 proposals for support from 53 received through a joint research call.

CSP Functional Genomics Call OngoingThe CSP Functional Genomics call is to enable users to perform state-of-the-art functional genomics research and to help them translate genomic information into biological function. Proposals submitted by January 31, 2019 will be part of the next review.

Learning to LookUsing machine learning, JGI researchers combed through more than 70,000 microbial and metagenome datasets, ultimately identifying more than 10,000 inovirus-like sequences compared to the 56 previously known inovirus genomes.

JGI Early Career Researchers in mSystems Special IssueJGI researchers are among the authors who offer perspectives on what the next five years of innovation could look like. In one article, Rex Malmstrom and Emiley Eloe-Fadrosh outline more targeted approaches to reconstruct individual microbes in an environmental sample. In a separate article, Simon Roux makes a pitch for readers to get involved in the developing field of virus ecogenomics.

Hidden Giants in Forest SoilsIn Nature Communications, giant virus genomes have been discovered for the first time in a forest soil ecosystem by JGI and University of Massachusetts-Amherst researchers. Most of the genomes were uncovered using a "mini-metagenomics" approach that reduced the complexity of the soil microbial communities sequenced and analyzed.

Viruses have a ubiquitous presence in the world. Their population is estimated to be 1031, 10 times greater than the nonillion (1030) of microbes on the planet—a figure that surpasses the number of stars in the Milky Way. Giant viruses are characterized by disproportionately large genomes and virions that house the viruses’ genetic material. They can encode several genes potentially involved in protein biosynthesis, a unique feature which has led to diverging hypotheses about the origins of these viruses. But after discovering a novel group of giant viruses with a more complete set of translation machinery genes than any other virus known to date, scientists at the U.S. Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science User Facility, believe that this group (dubbed “Klosneuviruses”) significantly increases our understanding of viral evolution.

The predicted hosts for the Klosneuviruses are protists – single-celled eukaryotic (nucleus-containing) microorganisms. And while their direct impacts on protists are not yet worked out, these giant viruses are thought to have a significant impact on these protists that help regulate the planet’s biogeochemical cycles. DOE JGI published the findings in the journal Science on April 7, 2017 with collaborators from the National Institutes of Health, University of Vienna, and CalTech.

“The discovery presents virus evolution for us in new ways, vastly expanding our understanding of how many essential host genes viruses can capture during their evolution,” said National Institutes of Health evolutionary and computational biologist Eugene Koonin, a study co-author whose lab collaborated with DOE JGI on analyzing the Klosneuvirus genome. “Since protein synthesis is one of the most prominent hallmarks of cellular life, it shows that these new viruses are more ‘cell-like’ than any virus anyone has ever seen before.”

Giant Viruses Have a Unique Ability

Scientists have been fascinated by giant viruses since 2003, when a group of French biologists led by Didier Raoult discovered the Mimiviruses. Since then, a handful of other giant virus groups have been found. The unique ability among them to encode proteins involved in translation (typically DNA to RNA to protein) piqued researchers’ interests as to the origin of giant viruses. Since then, two evolutionary hypotheses have emerged. One posits that giant viruses evolved from an ancient cell, perhaps one from an extinct fourth domain of cellular life. Another—a scenario championed by Koonin—presents the idea that giant viruses arose from smaller viruses.

Bubbling nitrifying activated sludge tank at a wastewater treatment plant in Klosterneuburg, Austria. This was the source of the sludge samples used for microcolony sorting. (Marton Palatinszky)

The discovery of Klosneuvirus supports the latter idea, according to Tanja Woyke, DOE JGI Microbial Genomics Program lead and senior author of the paper. “In this scenario, a smaller virus infected different eukaryote hosts and picked up genes encoding translational machinery components from independent sources over long periods of time through piecemeal acquisition,” she said.

At first glance, the suite of “cellular” genes in Klosneuvirus seemed to have a common origin, but when analyzing them in detail, the research team observed they came from different hosts. From the evolutionary trees the team built, they noticed that they were acquired by the viruses bit by bit, at different stages in their evolution. The Klosneuvirus genes contained aminoacyl-tRNA (transfer ribonucleic acid) enzymes with specificity for 19 out of 20 amino acids, along with more than 20 tRNAs and an array of translation factors and tRNA modifying enzymes—an unprecedented finding among all viruses, including the previously known giant viruses.

JGI postdoctoral researcher Frederik Schulz and Woyke unearthed Klosneuvirus while analyzing microcolony sequence data from a wastewater treatment plant sample in Klosterneuburg, Austria. This data was generated under a DOE JGI Community Science Program (CSP) project focused on the diversity of nitrifying bacteria for converting ammonia to nitrate in industrial and sewage waste treatment. “We expected genome sequences of nitrifying bacteria in the microcolony sequence data,” Woyke said. “Finding a giant virus genome took the project into a completely new and unexpected, yet very exciting direction.”

When Schulz, the study’s first author, noticed that several of the metagenomes were viral in origin, he and Woyke conducted analyses to determine their source. They found that the Klosneuvirus group came from a novel viral lineage affiliated with Mimiviruses.

“Mining sequence data in DOE JGI’s Integrated Microbial Genomes & Microbiomes (IMG/M) system, which houses thousands of metagenomes, allowed us to find evolutionary relatives of our Klosneuvirus,” Schulz said. He notes that while the metagenomic discovery of Klosneuviruses helped answer important evolutionary questions, the actual biological function of the translation system genes remains elusive—at least until these viruses are grown in the laboratory together with their hosts.

And Koonin believes there are more giant viruses waiting to be discovered in metagenomic data. “I’m quite confident that the current record of the genome size of giant viruses will be broken,” he says. “We are going to see the real Goliaths of the giant virus world.”

DOE’s Office of Science is the largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.